The present invention relates to a head slider which is used in a magnetic disk drive or the like. The head slider mounts a recording/reproducing element and is also arranged on a recording medium to fly over the recording medium owing to the airflow generated by movement of the recording medium.
In more specific, the present invention relates to a head slider having projections at the sliding surface, which are suitable for avoiding the stiction between the head slider and the recording medium.
FIGS. 1(a)-(c) show a magnetic head slider of the prior art. In the prior art, the magnetic head slider has floating rails 41 and 42, in the longitudinal direction, just opposed to a magnetic disk 3 when it is built into a magnetic disk drive. The magnetic head slider flies over the magnetic disk 3 when the airflow generated by rotation of the magnetic disk 3 enters into an air inflow end 5 and affects the floating rails 41-43, and then conducts the recording/reproducing operation to and from the magnetic disk 3 with an electromagnetic transducer 2 arranged at the area near the air outflow end 7.
It is effective to reduce the contact area of the magnetic head slider in order to prevent the stiction at the time of contacting with a CSS (Contact Start Stop) zone, therefore, projections 61-64 are provided on the rail surfaces of the floating rails 41 and 42. As shown in FIG. 1(b), in order to effectively prevent the stiction while the projections 61-64 are contacting with the magnetic recording, the height H of the projections 61-64 must be necessarily at least 20 nm for the magnetic disk 3 having Ra (average roughness) of about 2 nm. It has been verified experimentally that the stiction cannot be prevented if the height H is less than such value.
However, the prior art explained above has following disadvantages. The magnetic head slider takes a flying condition that the flying height of the air inflow end 5 is higher than one of the air outflow end 7 as shown in FIG. 1(c). If the electro-magnetic transducer 2 is attempted to be located near the magnetic disk 3 by reducing the flying height xcex4 of the magnetic head slider in view of enhancing the recording/reproducing sensitivity, the projections 63 and 64 near the air outflow end 7 may interfere with the surface of the magnetic disk 3. Moreover, in order to prevent the interference of the projections 63 and 64, it is thought to set up the pitch angle of the magnetic head slider, but it is disadvantage in the viewpoint of balance of the flying condition.
It is an object of the present invention to provide a head slider suitable for preventing the stiction to a recording medium.
It is another object of the present invention to provide a head slider which realizes the small flying height while preventing the stiction to a recording medium.
It is further object of the present invention to provide a head slider which achieves the small flying height and improves the recording/reproducing sensitivity to a recording medium.
The objects explained above can be achieved by a head slider which mounts a recording/reproducing element and flies over the recording medium with the airflow generated when the recording medium moves. This head slider comprises a slider body having the air inflow end and an air outgoing end, a rail which is projected from the slider body to define an air bearing surface extended to the outflow end, a projection formed on the rail and between the inflow end and the outflow end, and a recess formed at the outflow end of the rail to make narrow the width of the rail.
According to the present invention, when the recording medium stops to move, the head slider and the recording medium are in contact each other at the projection and the air outflow end of the rail. Since the air outflow end of the rail is rather narrow in width, the stiction can be prevented. Moreover, it is no longer required to form a projection near the outflow end of the rail and therefore the flying height of the recording/reproducing element can be lowered to improve the recording/reproducing sensitivity.
According the other aspect of the present invention, the width of the recording/reproducing element at the surface opposed to the recording medium is narrower than the width of the outflow end of the rail. According to this aspect, the recording/reproducing element is never exposed to the side wall of the recess of the rail and thereby the corrosion of the recording/reproducing element can be prevented.
According to still another aspect of the present invention, the rail comprises a couple of rails, and the width of one rail, where the recording/reproducing element is formed, at the outflow end is wider than the corresponding one of the other rail. According to this aspect, the width of the outflow end of the one rail is set so that the recording/reproducing element is never exposed. Moreover the width of the outflow end of the other rail can be set so that the stiction never occurs.
Moreover, according to still further aspect of the present invention, the recess isolates an area, where the recording/reproducing element is formed, from the air bearing surface of the rail and thereby the area is formed like an island. According to this aspect, the phenomenon that the lubricant creeps up can be prevented, therefore, the stiction can be prevented effectively.
Moreover, according to still further aspect of the present invention, a forward projection and a backward projection are provided on the rail. According to this aspect, the area in which the head slider is in contact with the recording medium can be reduced, therefore, the stiction can be prevented effectively. Namely, the head slider is in contact with the recording medium in the following three condition, first the inflow end and the forward projection, secondly the forward projection and the backward projection, and thirdly the backward projection and the outflow end are in contact with the recording medium. Even in any type of contact condition, the contact area between the head slider and recording medium can be reduced.